New to clicker training

Hi! We just adopted a ~2 year old rescued street dog and I just started clicker training.

My old training style was misguided and authoritarian. I am absolutely DONE with that, and learning how to set boundaries with dogs and keep training positive and supporting her healing journey. She’s gaining confidence everyday. She’s been with us just 4 weeks.

So I started clicker training for crate training her.

She’s fairly nervous about the crate, so we are making everything positive. Do I mark when she makes movement forward (such as front feet in)? Or should I wait until it’s more what “load up” actually means (whole body in)?

(I went through the guide, but this is a specific aspect of clicker training I’m confused about in this application.)